mirror of https://github.com/status-im/consul.git
57 lines
2.3 KiB
Markdown
57 lines
2.3 KiB
Markdown
---
|
|
layout: "docs"
|
|
page_title: "Commands: Event"
|
|
sidebar_current: "docs-commands-event"
|
|
---
|
|
|
|
# Consul Event
|
|
|
|
Command: `consul event`
|
|
|
|
The event command provides a mechanism to fire a custom user event to an
|
|
entire datacenter. These events are opaque to Consul, but they can be used
|
|
to build scripting infrastructure to do automated deploys, restart services,
|
|
or perform any other orchestration action. Events can be handled by
|
|
[using a watch](/docs/agent/watches.html).
|
|
|
|
Under the hood, events are propogated using the [gossip protocol](/docs/internals/gossip.html).
|
|
While the details are not important for using events, an understanding of
|
|
the semantics is useful. The gossip layer will make a best-effort to deliver
|
|
the event, but there is **no guarantee** delivery. Unlike most Consul data, which is
|
|
replicated using [consensus](/docs/internals/consensus.html), event data
|
|
is purely peer-to-peer over gossip. This means it is not persisted and does
|
|
not have a total ordering. In practice, this means you cannot rely on the
|
|
order of message delivery. An advantage however is that events can still
|
|
be used even in the absense of server nodes or during an outage.
|
|
|
|
The underlying gossip also sets limits on the size of a user event
|
|
message. It is hard to give an exact number, as it depends on various
|
|
parameters of the event, but the payload should be kept very small
|
|
(< 100 bytes). Specifying too large of an event will return an error.
|
|
|
|
## Usage
|
|
|
|
Usage: `consul event [options] [payload]`
|
|
|
|
The only required option is `-name` which specifies the event name. An optional
|
|
payload can be provided as the final argument.
|
|
|
|
The list of available flags are:
|
|
|
|
* `-http-addr` - Address to the HTTP server of the agent you want to contact
|
|
to send this command. If this isn't specified, the command will contact
|
|
"127.0.0.1:8500" which is the default HTTP address of a Consul agent.
|
|
|
|
* `-datacenter` - Datacenter to query. Defaults to that of agent.
|
|
|
|
* `-name` - The name of the event.
|
|
|
|
* `-node` - Regular expression to filter nodes which should evaluate the event.
|
|
|
|
* `-service` - Regular expression to filter to only nodes with matching services.
|
|
|
|
* `-tag` - Regular expression to filter to only nodes with a service that has
|
|
a matching tag. This must be used with `-service`. As an example, you may
|
|
do "-server mysql -tag slave".
|
|
|